.. code-block:: python

	#!/usr/bin/env python
	
	
	from __future__ import print_function
	import sys
	import pymzml
	import os
	
	
	
	def main():
	    """
	    Demonstration of the extraction of a specific ion chromatogram, i.e. XIC or EIC
	
	    All intensities and m/z values for a target m/z are extracted.
	
	    usage:
	
	        ./extract_ion_chromatogram.py
	
	    """
	
	    example_file = os.path.join(
	        os.path.dirname(__file__),
	        os.pardir,
	        'tests',
	        'data',
	        'example.mzML'
	    )
	    run = pymzml.run.Reader(
	        example_file
	    )
	    time_dependent_intensities = []
	
	    MZ_2_FOLLOW = 70.06575775
	
	    for spectrum in run:
	        if spectrum.ms_level == 1:
	            has_peak_matches = spectrum.has_peak( MZ_2_FOLLOW )
	            if has_peak_matches != []:
	                for mz,I in has_peak_matches:
	                    time_dependent_intensities.append(
	                        [
	                            spectrum.scan_time_in_minutes(),
	                            I,
	                            mz
	                        ]
	                    )
	    print('RT   \ti   \tmz')
	    for rt, i, mz in time_dependent_intensities:
	        print(
	            '{0:5.3f}\t{1:13.4f}\t{2:10}'.format(
	                rt,
	                i,
	                mz
	            )
	        )
	    return
	
	if __name__ == '__main__':
	    main()
